Abstract: An improved method for simplifying a slip casting applied conventional all ceramic core molding process by molding an all ceramic core from a ceramic sheet. In the method, there is prepared a slurry which consists mainly of alumina, spinel, alumina/zirconia powder, by adding thereto a dispersant, a binding agent, a plasticizer, a solvent and the like. The slurry is formed into a sheet having a thickness of 0.1 mm to 1.0 mm for thereby fabricating a tooth molding mass by using a heat hydrostatic pressing at a pressure of 15 Kgf/cm.sup.2 to 150 Kgf/cm.sup.2 at a temperature of 50.degree. C. to 110.degree. C., with slurry composition for fabricating an all ceramic jacket crown applicable to an artificial crown.

Abstract: An optical switch having reduced processing errors in a coupling region, according to the claimed invention includes an input portion having a pair of optical waveguides; an output portion having a pair of optical waveguides; a light phase shifting portion for inducing an additional phase change on light travelling in the input portion; a first light coupling waveguide for coupling between two light signals of the input portion and for providing a coupled signal with the light phase shifting portion; and a second light coupling waveguide for coupled between two light signals of the light phase shifting means and for providing a coupled signal with the output portion. The light coupling unit includes a waveguide. The switch reduces considerably any error that stems from manufacturing variations between waveguides in a coupling region since the waveguides share the error produced in a coupling region.

Abstract: An improved method for simplifying a slip casting applied conventional all ceramic core molding process by molding an all ceramic core from a ceramic sheet. In the method, there is prepared a slurry which consists mainly of alumina, spinel, alumina/zirconia powder, by adding thereto a dispersant, a binding agent, a plasticizer, a solvent and the like. The slurry is formed into a sheet having a thickness of 0.1 mm to 1.0 mm for thereby fabricating a tooth molding mass by using a heat hydrostatic pressing at a pressure of 15 Kgf/cm.sup.2 to 150 Kgf/cm.sup.2 at a temperature of 50.degree. C. to 110.degree. C., with slurry composition for fabricating an all ceramic jacket crown applicable to an artificial crown.